The present invention relates to machines and processes for the casting of discrete solid shapes from a flowable, moldable or molten material. Specifically, the invention discloses continuously casting discrete shapes using a static mold casting machine or, preferably, a moving mold casting machine where, for example, the shapes are formed between spaced portions of a pair of endless flexible casting belts which are moved along with opposite surfaces of the metal being cast.
Although the principles of the invention can be used to cast any flowable, moldable or molten material such as plastics, the invention will be described in terms of continuously casting molten metal into discrete and variable shapes, such as ingots, anodes, wirebars or foundry castings.
Discrete metallic shapes are typically cast in individual molds using a discontinuous stream of molten metal. A plurality of mold cavities are supplied sequentially and the flow of metal in the desired quantity to each of the molds is controlled manually by an operator or in an automated manner. Continuous casting is employed, in a variety of forms, in the nonferrous and ferrous metals industry and elsewhere, to decrease production cost and increase product quality. Two basic systems known as the static and moving mold methods are used in continuous casting of shapes such as billets or continuous strips. In the static mold casting machine, the walls of the mold are stationary, while the cast products move against and solidify within them. Moving mold casting machines employ a belt, chain, drum, wheel, or other surface which moves at approximately the same speed as the solidifying metal.
The continuous casting of metal on moving mold casting machines having at least one movable belt and a corresponding fixed or movable surface which together form a mold of two opposed surfaces in which the cast material solidifies is described in detail in the following U.S. Pat. Nos. which are incorporated herein by reference: 2,631,343; 2,904,860; 3,036,348; 3,123,873; 3,123,874; 3,167,830; 3,533,463; 3,864,973; 3,878,883; 3,921,697; 3,937,270; 3,937,274; 3,949,805; 3,955,615; 4,002,197; and 4,854,371.
For a twin belt caster where two movable belts form the mold, in operation, a continuous stream of molten metal is supplied at the inlet of the machine to a cavity formed by a pair of movable flexible casting belts, positioned generally above the other, and side dam blocks, and emerges at the other end of the cavity (outlet of the machine) as a solidified strip or bar of metal. The strip or bar is subsequently fed to other apparatus for mechanical working, or cutting and/or welding, which changes its cross sectional dimensions. For example, twin belt casters of the type described are used to convert molten copper to a roughly rectangular bar shape which is then continuously fed to a rolling mill having a series of rolling stages for converting the rectangular bar to a round rod. Typically, the rod eventually is drawn to wire of various gauges.
In a previous attempt in the art to produce shaped articles continuously, a twin belt caster was modified by making the dam blocks smaller at certain intervals to provide a cast material having the shape of an anode, i.e., a flat rectangular shape having support arms. After casting, however, the casting had to be cut to form discrete anode shapes.
Another continuous casting moving mold method employs a casting wheel having a peripheral groove therearound. A portion of the peripheral groove is closed by an endless belt to form a mold into which molten metal is poured to be solidified into cast metal and discharged therefrom. Such designs may be seen in U.S. Pat. Nos. 3,279,000 and 3,469,620, which patents are hereby incorporated by reference.
Continuous casting using a static mold may be found in U.S. Pat. Nos. 2,938,251; 2,946,100; 3,066,364; 3,089,209; 3,098,269; and 3,115,686, which patents are hereby incorporated by reference. Basically, molten metal is continuously fed into the mold, freezes and the frozen product continuously removed from the mold. Generally, the mold is in a vertical position with the molten metal poured into the top of the mold.
While the casting machines described hereinabove are very successful and employed extensively throughout industry, the need still exists for these type continuous casting machines to produce discrete shapes. It is an object of the invention to provide apparatus and methods for the continuous casting of such discrete shapes.